GM Service Manual Online
For 1990-2009 cars only

Both the driver and passenger full feature seats have 2 heating elements. One is in the seat cushion and one in the seat back. The heated seats are capable of obtaining temperatures of 37°C (98°F) in low and 42°C (107°F) in high. Power is supplied to both heated seat switches via CKT 541 (BRN) from the IGN 3 fuse (located in the fuse block). The ground path is supplied via CKT 1850 (BLK) to G203. When the heated seat switch is turned on, power is supplied to the electronic driver heated seat relay (integrated circuit) via CKT 1462 (LT BLU) and CKT 1505 (LT BLU/BLK) for the electronic passenger heated seat relay. The electronic relay is permanently grounded via CKT 2350 (BLK) to G304. Power is also supplied to the electronic heated seat relay via CKT 2340 (ORN) from the SEO 2 fuse (located in the engine wiring harness junction block) which supply power to the two heating elements. The system is controlled by a driver thermistor which sends a signal to the heated seat relay logic and controls the operation of the heating elements.